The dog is asleep and uninterested when the cat is getting up on the futon with my niece - he actually seems to be acting like a normal cat at these times. There are times during the day/evening when the cat will sit with my niece or allow her to pet him while he's walking by or whatever - it's just from time to time over the past 3-4 days that he has taken a swipe at her when she walks by.
She did mention last night that he only seems to do it if she's wearing a certain pair of sweatpants she often wears to bed. My half cocked (watch it!) theory is because they are wide legged pants that swing and he may think the dog is coming around behind her when it is actually the movement of the pants...